Fastener members, having a flange portion and a hollow barrel portion with a flarable end, are known and are commonly referred as tee-nuts, or rivet type tee-nuts. In In this specification, the term "tee-nut" is used to describe such fastener members.
Such tee-nuts are usually formed of sheet metal, and provide a flanged portion, a threaded sleeve or barrel portion, and a plurality of fastening teeth or prongs, all formed out of a single piece of sheet metal.
Typically such tee-nuts are used, for example, in furniture frame, for fastening the arms and legs of the furniture to the frame. They do have a variety of other uses, both in furniture and in many other industries.
U.S. Pat. No. 5,348,432 granted to Nagayama on Sep. 20, 1994 discloses a tee-nut having a sleeve in the form of a hollow cylinder with a relatively thin-walled flarable end portion and a relatively thicker-walled threaded portion. The thin-walled flarable hollow sleeve end is formed by counter boring an entirely internally threaded hollow sleeve. The disadvantage of this product is that counter boring is uneconomical to perform. Also, tiny metal scraps are likely to be left behind within the internal threads. Also, when flared outwardly, the flarable counter-bored end has a tendency to split.